JP2008502485A - Continuous butt welding method using plasma and laser, and metal pipe manufacturing method using the same - Google Patents

Abstract

  A continuous butt welding method using a plasma and a laser and a metal tube manufacturing method using the same are disclosed. In the welding method of the present invention, laser welding and plasma welding are performed on a workpiece to be welded with a very narrow butt interval, and in particular, after the plasma is preheated by plasma with the laser preceding the laser, the laser beam is used. Main welding is performed by melting the base material. Further, a metal tube is manufactured by bending a metal plate material into a circular cross section so that both sides are opposed to each other and welding the opposite sides by the above-described welding method. According to the welding method and the metal pipe manufacturing method of the present invention, the welding speed and the productivity of the metal pipe are remarkably improved.

Description

  The present invention relates to a butt welding method of a metal material and a manufacturing method of a metal tube using the same, and more particularly, a welding method in which welding speed is improved by welding using two heat sources simultaneously. And a method of manufacturing a metal tube.

  Laser welding and arc welding have been widely used to butt two metal materials together and join them together. Laser welding can focus the heat source (laser beam) very small, has a small heat-affected zone during welding, enables precision welding of delicate parts, and produces seam welding (key hole) There is an advantage that deep penetration welding is possible. However, the narrow focal radius of the laser makes it difficult to follow elaborate welding lines such as butt welding, and there are also disadvantages such as making the keyhole unstable and generating pores in the weld. In addition, when laser welding is used, a high-power laser must be used to increase the welding line speed in order to increase productivity, which leads to a significant increase in welding costs.

  On the other hand, arc welding and plasma welding have the advantages of fewer weld defects and easier tracking of weld lines than laser welding. However, arc welding, in particular, has a disadvantage that it is not suitable for welding precision products with a narrow butt interval (for example, 0.2 mm or less) because the heat source area of the welded portion is large.

  In order to overcome the disadvantages of these two welding methods, a welding method (Patent Document 1, Patent Document 2, Patent Document 3, etc.) in which laser welding and arc welding are performed in parallel has been proposed. These Japanese and US patent publications allege that by using laser welding and arc welding together, deep penetration that could not be obtained by arc welding can be obtained, and effects such as increased welding speed can be obtained. Yes. However, the simultaneous use of two heat sources does not necessarily bring only the advantages. Depending on the posterior relationship between the two heat sources, the distance, angle, power, and welding speed, the effect of using each heat source alone can be reduced. The result may be just a combination.

On the other hand, welding is used to manufacture a metal tube (a so-called loose tube, usually made of stainless steel) in which a plurality of optical fibers are gently incorporated. That is, a metal tube is manufactured by plastic-working a strip-shaped metal plate material so that the cross section is substantially circular, and welding and joining the opposing end portions. Usually, such a loose tube has a diameter of 2 to 5 mm, a thickness of 0.1 to 0.2 mm, and a butt interval before welding of 0.2 mm or less and requires very elaborate welding. . Therefore, at present, laser welding using a CO ₂ laser is used as welding at this time. However, as described above, there is a limit to improvement in productivity only by laser welding. That is, the welding speed cannot catch up with the speed at which the metal plate material is plastically processed so as to have a substantially circular cross section, and the welding process can be a rate-limiting process (bottleneck process).

  Therefore, a method of improving the welding speed by simultaneously using two heat sources, such as the combined welding of laser welding and arc welding described above, can be considered. However, as described above, the simultaneous use of the two heat sources can not only achieve the desired effect for the first time through the management of very complicated process conditions, but also the selection of the heat source and the process conditions for each property of the material to be welded. Must be set. For example, the laser and arc combined welding disclosed in the Japanese and US patent publications mentioned above is used for welding relatively thick plate materials and general steel plates other than stainless steel, such as the bodies of ships and automobiles. This technique is used and has a very small butt interval and is unsuitable for welding a material to be welded for a thin plate.

  Thus, there has been a demand for a welding method capable of performing elaborate welding while improving the welding speed for butt welding of a metal plate material with a very small butt interval such as a loose tube and intended for a thin plate. .

JP 2001-334377 A JP 2002-346777 A US Patent Application Publication 2001/0047984 A1

  An object of the present invention is to provide a welding method capable of performing elaborate welding while improving the welding speed for a material to be welded having a very small butt interval and a thin plate in response to the above-described requirements. .

  Another object of the present invention is to provide a method of manufacturing a metal tube having a small diameter by butt welding a thin metal plate material having a very small butt interval.

  In order to achieve the above technical problem, as a welding method according to the present invention, laser welding and plasma welding are both used. In particular, plasma welding is performed before laser welding, and a base material (covered material) is formed by plasma. After preheating the welding material, the base material is melted with a laser beam and main welding is performed.

  That is, in the continuous butt welding method using plasma and laser according to one aspect of the present invention, first, a material to be welded having welded portions facing each other is continuously supplied, and the welded portion is subjected to a plasma torch. After preheating using the laser beam, the welded portion preheated by the plasma torch is irradiated with a laser beam for welding.

  In the present invention, the plasma torch and the laser head are preferably arranged so that the distance between the center of the heat input region by the plasma torch and the center of the heat input region by the laser beam is 0.5 to 2.5 mm. .

  The welding method of the present invention is particularly suitable for welding materials to be welded, in which the butt interval between welds facing each other is 0.2 mm or less.

  The welding method of the present invention can be suitably applied particularly to stainless steel, but can also be applied to butt welding of nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium alloy, mild steel, or low alloy steel.

  Further, the above-described welding method can be applied to the production of a metal tube having a relatively small thickness and diameter. That is, the method of manufacturing a metal tube according to another aspect of the present invention includes a step of continuously supplying a strip-shaped metal plate material, a step of processing the metal plate material into a tubular shape so that both side portions thereof face each other, and a processing of the tubular shape And preheating the welds facing each other using a plasma torch, and irradiating the welds preheated by the plasma torch with a laser beam.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms and words used in this specification and claims should not be construed in a normal, lexicographic sense, and the inventor will explain the invention in the best possible manner. Therefore, it must be interpreted in the meaning and concept corresponding to the technical idea of the present invention in accordance with the principle that the concept of the term can be appropriately defined. Accordingly, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. It should be understood that there are various equivalents and variations that can be substituted at this point.

  FIG. 1 is a schematic perspective view illustrating an apparatus for manufacturing a metal pipe by a welding method and a metal pipe manufacturing method according to an embodiment of the present invention, and FIG. 2A is a cross-sectional view taken along line AA of FIG. 2b is a sectional view taken along line BB in FIG.

Referring to FIGS. 1, 2a and 2b, the process of manufacturing a metal tube according to the present embodiment will be described. First, a metal plate 10 having a predetermined width and thickness is moved at a constant speed in the direction of arrow x. Supply with. Then, the shaping | molding means 20 carries out plastic working of the both sides of the metal plate material 10, and bends it into the tubular shape whose cross section is circular. As shown in FIG. 2a, the metal tube 10 'formed into a tubular shape with a predetermined butt interval d is welded along the weld line 10a by the plasma torch 30 and the laser head 40, and is shown in FIG. 2b. As shown, the metal pipe 10 "is joined at the weld. In the configuration shown in FIG. 1, the metal plate 10 and the metal pipes 10 'and 10" before and after welding proceed as a single unit, forming means. 20, since the plasma torch 30 and the laser head 40 are fixed, the supply speed of the metal plate 10 becomes the welding speed. However, which of the metal plate material 10, the forming means 20, the plasma torch 30 and the laser head 40 is fixed and which is moved can be appropriately changed according to the apparatus configuration and work environment. When the plasma torch 30 and the laser head 40 are moved, the metal plate supply speed and the welding speed can be made different.

  In the present embodiment, the metal plate material 10 will be described with reference to stainless steel having the following physical properties and dimensions. However, the material and dimensions of the metal plate material may be arbitrarily changed depending on requirements. Is possible. That is, the metal plate 10 may be made of nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium alloy, mild steel, or low alloy steel in addition to stainless steel.

Physical properties and dimensions of metal plate at normal temperature Density: 7200 kg / m ³
Conductivity: 14.9 W / mK
Specific heat: 477J / kgK
Melting point: 1670K
Melting latent heat: 247 kJ / kg
Boiling point: 3000K
Vaporization latent heat: 7000 kJ / kg
Metal plate thickness: 0.2mm
Metal plate width: 13.5mm
Diameter of molded metal tube: 4.3mm

  In FIG. 1, the forming means 20 is shown as two pairs of opposing rotating forming rollers, but the number of roller pairs is not limited to the number shown. Further, in the present embodiment, the forming roller 20 is shown to be bent into a metal tube having a circular cross section of the metal plate member 10, but may be a metal tube 10 ′ having an elliptical cross section, for example. .

  As shown in FIG. 2a, the metal tube 10 ′ before welding bent into a tubular shape by the forming means 20 forms a V-shaped groove in which the welds facing each other form a butt interval. Although d is approximately 0.15 mm and the angle θ of the V-shaped groove is approximately 10 °, d and θ also vary depending on the size of the metal plate 10 and the shape of the forming means 20. In particular, θ can be made very small as 5 ° or less.

  Unlike a normal arc welder, the plasma torch 30 used in the present invention has a small plasma dispersion angle and enables high-precision and high-density welding. That is, plasma welding is similar to TIG (Tungsten Inert Gas) welding, but in the plasma torch 30, a tungsten welding rod is built in the nozzle of the copper electrode, and the pilot gas and the gas of the water-cooled copper nozzle are added. The gas shrinks due to the cooling effect, and the plasma dispersion angle can be reduced more than the arc dispersion angle in TIG welding. Further, the efficiency of the plasma, that is, the ratio of the electric power (heat) emitted from the end (cathode) of the plasma torch 30 and absorbed by the base material surface (anode) is 60% or more, and the efficiency is usually 43%. Higher efficiency than TIG welding, and less contamination and wear of the welding rod. In this embodiment, the plasma welding machine is 80A or less and is operated with a supply voltage of 20 to 30V. Depending on the type and dimensions of the base material or the welding speed, other standard torches can be used. Of course.

In this embodiment, the laser welder uses a CO ₂ laser having an output of 680 W and an effective diameter of the laser beam at the focal position of approximately 0.5 mm, depending on the type and size of the base material or the welding speed. Of course, it is possible to use laser welding machines of other standards.

On the other hand, in the present invention, the welded metal tube 10 ″ as shown in FIG. 2b is obtained by welding the metal tube 10 ′ along the weld line 10a using the plasma torch 30 and the laser head 40 together. Although it is manufactured, the positional relationship between the plasma 30a by the plasma torch 30 and the laser beam 40a by the laser head 40, the distance x _off between them, the incident angle between the plasma 30a and the laser beam 40a, and the like are the welding speed and welding. The factors that affect the welding performance will be described in detail.

  First, as shown in FIGS. 3a and 3b, the plasma torch 30 is used while being inclined at about 45 ° with respect to the surface of the base material 10 ′. At this time, the heat input energy by the plasma on the surface of the base material is used. The distribution will be described.

  If the plasma 30a is perpendicularly incident on the flat base metal surface, the heat input energy distribution I (r) by the plasma should be Gaussian as shown in the following equation 1, but is incident obliquely on the base metal surface. In this case, the plasma heat input region (see 30b in FIG. 4) on the surface of the base material becomes a long ellipse along the traveling direction x of the base material, and the heat input energy distribution at this time is as shown in Equation 2 below. Become.

Here, I ₀ is a peak energy density, r is a radial distance in the heat input region, r ₀ is an effective radius of the heat input region, and c is a degree of concentration in which the plasma energy is distributed in r ₀ . On the other hand, in the following explanation, since the dispersion angle of plasma is negligible, it will be explained by calculating 0 ° (that is, assuming that the plasma is a cylinder).

Here, θ _t is the angle of incidence of the plasma, a is the major axis length of the ellipse, r ₀ / sin θ _t , b is the minor axis length of the ellipse, b = r ₀ , x is from the center of the ellipse The distance in the major axis direction, y is the distance in the minor axis direction from the center of the ellipse.

  On the other hand, the above formulas 1 and 2 are the energy density when the plasma is incident on the surface of the flat base material. In fact, in this embodiment, the plasma 30a is incident on the V-shaped groove at the center. . Therefore, it is necessary to consider the heat input energy distribution of the plasma incident on the inside of the V-shaped groove. However, since the plasma is a mass flow, the flow inside the V-shaped groove is considerably complicated. Analysis of the phenomenon is extremely difficult. Therefore, here, the heat input energy distribution on the wall surface of the V-shaped groove is constant with respect to the plasma traveling direction, and is Gaussian distributed with respect to the moving direction of the torch (actually the moving direction x of the base material). Assuming a simplified state. That is, it is assumed that the plasma heat input energy density in the depth direction along the wall surface of the V-shaped groove is constant.

  The heat input energy distribution by the laser beam 40a of the laser head 40 is the same as expressed by the above equation 1 if the laser beam is incident on the surface of the flat base material perpendicularly. However, since the energy of the laser beam is absorbed and sometimes reflected by the surface of the base material, this must be taken into consideration. The absorption rate of the laser beam on the surface of the base material varies depending on the characteristics of the laser beam and the material and characteristics of the base material, but also depends on the incident angle of the laser beam. According to the Fresnel absorptance equation, the laser beam exhibits the highest absorptance when the incident angle is about 85 °. That is, the maximum absorption rate can be obtained when the laser beam is tilted with respect to the base material and irradiated almost parallel to the surface of the base material. Here, it should be noted that in order to obtain the maximum absorption rate, in FIG. 3a or 3b, the laser head 40 must be tilted so as to be almost parallel to the base material 10 ′. I'm not. As described above, the welded portion of the base material 10 ′ of the present embodiment is a V-shaped groove having a butt interval d of about 0.15 mm, and most of the laser beam 40a is irradiated to the inside of the V-shaped groove. (See 40b in FIG. 4). Further, since the V-shaped groove has the included angle θ of about 10 ° as described above, when the laser head 40 is arranged substantially perpendicular to the surface of the base material 10 ′ in FIG. The incident angle of the laser beam incident on the wall surface of the letter-shaped groove is approximately 85 °. However, since the laser beam applied to the surface of the base material 10 ′ outside the V-shaped groove is reflected and may damage the laser head 40, the laser head 40 is used as shown in FIGS. 3a and 3b. It is desirable to place it at a slight angle.

On the other hand, when the laser beam is irradiated inside the V-shaped groove in this way, the energy distribution input to the wall surface inside the V-shaped groove is explained by the multiple reflection effect. That is, as shown in FIG. 5, the laser beam 40a incident on the V-shaped groove undergoes multiple reflections on the inner wall surface, and as a result, has only a very small energy and is reflected to the outside of the groove. Go. The number of multiple reflections inside the V-shaped groove increases as the groove angle is smaller. However, according to the calculation by the present inventor, when the groove angle is 20 °, reflection is performed about eight times. In each of the eight reflections, since the incident angle of the laser beam with respect to the wall surface changes, the absorptance at each reflection should also change, but the average absorptance at one reflection is 0 on average. Assuming .5, the energy of the laser beam that goes out of the groove after eight reflections falls below 0.4% of the initial incident energy (0.5 ⁸ ≈0.0039). That is, it can be said that almost all of the energy is absorbed inside the V-shaped groove. Moreover, since the recovery of reflection increases as the depth increases along the wall surface of the V-shaped groove, and the energy density is highest in the central portion of the heat input region 40b (see 40c in FIG. 5), the V-shaped groove The heat input energy distribution inside becomes maximum at the lowest part of the groove and decreases as it goes upward.

  On the other hand, according to the experiment according to the present invention, the overall energy absorption rate (efficiency) inside the V-shaped groove was different depending on the angle θ of the V-shaped groove (after all, depending on the change in the incident angle of the laser beam). It was found that when θ was 10 °, the efficiency was about 35%, the maximum efficiency was shown at 20-40 °, and the efficiency was about 15% almost the same as that of a simple flat plate at 120 ° or more. In the above analysis, the smaller the θ, the more the multiple reflections occur, so the efficiency should be higher. However, the smaller the θ, the higher the ratio of the energy concentrated outside the V-shaped groove in the heat input region 40b. Since the absolute incident amount to the inside of the groove is reduced, the above result is considered.

  The above analysis on the plasma heat input energy distribution and the laser heat input energy distribution is an analysis result when each heat source is used alone. When the two heat sources are used together, the heat input energy distribution is considered to be a value obtained by superimposing the respective heat input energy distributions if the two heat sources interfere with each other.

In order to confirm the coherence of the two heat sources, the following simple experiment was conducted. First, only the laser beam is vertically incident on the surface of the flat base material, and the energy incident on the surface of the base material is measured. At this time, the laser beam is defocused so as to be focused slightly above the surface of the base material. Thereafter, plasma is superimposed on the focal position of the laser beam perpendicularly to the laser beam (that is, in a direction parallel to the surface of the base material), and the energy incident on the surface of the base material at this time is measured. As a result, the energy measured when only the laser beam was irradiated was 41 W, and the energy measured when the plasma was interfered was 40 W. That is, when two heat sources are simultaneously superimposed, the laser beam is slightly absorbed by the plasma column, although only slightly. At the same time, considering that this result is not a measurement when the laser beam and the plasma column are superimposed on the base metal surface, that is, considering the interference of welding when superimposing on the base metal surface, the two heat sources are simultaneously When used, it can be determined that it is better to provide a small distance x _off between the centers of the heat input regions 30b and 40b by the two heat sources. However, if the distance x _off between the two heat input regions is excessively increased, the preheating effect by the preceding heat source should be reduced, and this must also be avoided. The optimum value of x _off varies depending on the process conditions such as the output of the plasma torch and laser welder and the welding speed, but the specific value is calculated through an experimental example to be described later.

On the other hand, when two heat sources are used at the same time, if the interference between the two heat sources is avoided, the heat input energy distribution should increase compared to when each heat source is used alone, the overall heat input energy distribution. I think that it is desirable to have more than simply integrating the heat input energy distribution. Therefore, the synergistic effect by the simultaneous use of these two heat sources can be sought preferably by preheating with plasma and increasing the absorption rate of the laser beam. That is, it has been described above that the laser beam absorptance varies depending on the incident angle of the laser beam with respect to the surface of the base material, but the laser beam absorptance also depends on the temperature of the other base material. In the case of the stainless steel of this embodiment having the above-described physical properties, the absorption coefficient increases by about 3.5 × 10 ⁻⁵ when the temperature increases by 1 ° C. in the Fresnel absorption rate formula described above. Although this number seems to be trivial, when the temperature of the base material increases by, for example, 1000 ° C. due to plasma preheating, the absorption coefficient of the laser beam increases by 0.035, and the absorption coefficient at room temperature is about 0.08. Considering this, it can be said that the absorption rate is considerably increased.

  According to the above analysis, when two heat sources are used at the same time, the laser beam absorptivity is achieved by preheating the base metal by providing an appropriate distance between the heat input regions and causing the plasma to precede the laser. It can be seen that it is better to weld in the direction of increasing the. “Plasma is preceded by laser” means that when the base material 10 ′ is supplied along the traveling direction x, the plasma 30 a is first irradiated and then the laser beam 40 a is irradiated. As shown in FIG. 3a, the plasma torch 30 and the laser head 40 are arranged so as to face each other so that the plasma 30a and the laser beam 40a intersect (or pass each other), as shown in FIG. 3b. The plasma torch 30 and the laser head 40 are arranged in parallel directions, and the plasma 30a and the laser beam 40a are irradiated from the parallel directions.

  At this time, the included angle φ formed by the plasma 30a and the laser beam 40a is preferably within a range of about 70 ° in the case of FIG. 3A and within a range of about 50 ° in the case of FIG. 3B. On the other hand, when viewed from the traveling direction of the base material 10 ′, the discharge direction of the plasma 30a by the plasma torch and the irradiation direction of the laser beam 40a are ± 20 ° with respect to the V-shaped groove (that is, the welding line) of the base material 10 ′. It is preferable to have a corner within (see FIG. 3c). This is because if the plasma 30a or the laser beam 40a is ejected or irradiated at an excessively inclined angle, either one of the plasma 30a or the laser beam 40a is unevenly bonded, and the surface of the welded portion is uneven or incompletely bonded. Because there is a fear.

As described above, the distance x _off between the two heat sources, the positional relationship and the angle between the plasma torch 30 and the laser head 40 are appropriately adjusted, and at the same time the plasma 30a and the laser beam 40a are generated at a predetermined output, and the base material When 10 ′ is continuously supplied in the x direction, as shown in FIG. 4, first, a heat input region 30b is formed by the plasma 40a of the plasma torch 40, and the base material is preheated. As the base material advances, the preheating region 30c is tailed so as to have a tail behind the heat input region 30b by plasma, and the heat input region 40b by the laser beam 40a is formed inside the tail side of the preheating region 30c. It will be the form that follows. The preheated base material is melted in the heat input region 40b by the laser beam, and main welding is performed to continuously generate the beads 10b. Thus, the metal tube 10 ″ having a circular cross section is continuously manufactured from the metal plate material 10.

Hereinafter, with respect to the welding method of the present invention, results of confirming welding performance through various experiments will be described. First, the welding characteristics evaluated in the following experiment are defined with reference to FIG. FIG. 6 shows only a half region with the traveling direction of the base material 10 ′ as a boundary. Evaluation of weldability is may be other evaluation methods, by measuring the width (bead width) _{L B} of penetration depth (penetration depth) _{L A} and the bead B indicating the depth of the molten pool A Can be evaluated.

  In the following experiments, the stainless steel plate described in the description of the above-described embodiment was used as the metal plate material, and the angle of the V-shaped groove was set to 10 °. The plasma torch and the laser welding machine used the apparatuses described in the above-described examples.

The following experiments are conducted when welding is performed using only a plasma welder (Comparative Example 1), when welding is performed using only a laser welder (Comparative Example 2), and when two heat sources are used together with plasma preceding. (Example 1), and the case where two heat sources were used together with a laser preceding (Comparative Example 3). In Comparative Example 1 and Comparative Example 2, the plasma output and laser output were fixed, respectively, and the penetration depth and bead width were measured while changing the welding speed. In Example 1 and Comparative Example 3, welding was performed. The penetration depth and bead width were measured while changing the plasma output and the distance x _off between the two heat sources at a fixed speed. Each experimental result will be described as follows.

  First, as shown in FIG. 7a (the plasma current is fixed at 10A) and FIG. 7b (the plasma current is 15A), the results of Comparative Example 1 show that the penetration depth and bead width decrease as the welding speed increases. It became something to do. Since the thickness of the metal plate used in this experiment is 0.2 mm, assuming that the penetration depth is 0.2 mm or more and complete penetration, the welding speed is 4 for each of FIGS. 7a and 7b. It can be seen that complete penetration is not possible until 0.0 m / min or less and 6.0 m / min or less.

  Also in Comparative Example 2 shown in FIG. 8, as the welding speed increases, the penetration depth and the bead width decrease, and in order to cause complete penetration, the welding speed is about 5.0 m / min or less. I understand that I have to do it.

9a and 9b are graphs showing the results of Example 1 and Comparative Example 3, in which the welding speed was fixed at 12 m / min and the beads measured while changing the distance x _off between the two heat sources. It shows the width and penetration depth. In the drawing, LF and PF mean the case where laser is preceded and the case where plasma is preceded, respectively, and the current value after that indicates the current of the plasma welding machine.

As shown in FIGS. 9a and 9b, when two heat sources are used together, Example 1 when the plasma is preceded is superior to Comparative Example 3 when the laser is preceded. As a result. Further, it was confirmed that the weldability of Example 1 was excellent when x _off was 0.5 to 2.5 mm under the conditions as in this experiment.

  Thus, according to Example 1, the welding speed can be increased to 12.0 m / min, and the welding speed (6.0 m / min or less) at the time of welding using a conventional plasma alone and a laser alone are used. In addition to the welding speeds of the welding speeds (5.0 m / min or less) during welding, high welding speeds that clearly exceed the values obtained by simply integrating these welding speeds can be obtained.

  While the present invention has been described with reference to the embodiments and the drawings, various modifications and variations can be made without being limited to these limited descriptions. For example, in the above-described embodiments, the case where a metal tube is manufactured by bending and welding a metal plate material has been described. However, the present invention is not limited to a metal tube, and the welding method of the present invention can be applied.

  In the above-described embodiments, stainless steel is described as the base material (material to be welded), but other than that, nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium alloy, mild steel, low alloy steel It can also be applied to metal materials such as. Furthermore, in the above-described embodiments, since the metal plate materials are bent and face each other, the two materials to be welded are the same metal, but the welding method of the present invention is also applied to butt welding of metal materials having different compositions. it can. Of course, when the base material is a butt welding of a metal other than stainless steel or a metal material having a different composition, the output and welding speed of the plasma welding machine and the laser welding machine can be appropriately changed accordingly.

  Therefore, the scope of the present invention should be construed to extend to the equivalent scope of the claims. The configurations shown in the embodiments and drawings described in the present specification are only the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. It should be understood that there can be various equivalents and variations that can be substituted for these.

  As described above, according to the welding method of the present invention, by performing laser welding after pre-heat treatment with a plasma torch, the weldability and welding speed at the time of butt welding of materials to be welded with very narrow butt intervals are remarkably increased. It can be improved. In particular, expensive laser welding equipment has been required for accurate and rapid welding, but it is possible to maintain the accuracy of welding accuracy by performing both plasma welding and laser welding at low cost. The welding speed can be improved. Further, when laser welding alone is performed alone, it is necessary to accurately track the welding line and the workability is reduced. However, by performing plasma welding together, the workability is improved and the welding quality is also improved.

  In addition, the welding method of the present invention is suitable for manufacturing a metal pipe having a small thickness and diameter, and can be welded in accordance with the supply speed (plastic working speed) of the metal plate material. The process can be eliminated, and the productivity of metal pipe manufacturing can be greatly improved.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the detailed description of the embodiments, serve to explain the technical idea of the invention.
FIG. 1 is a schematic configuration diagram of an apparatus for manufacturing a metal pipe by a welding method and a metal pipe manufacturing method according to an embodiment of the present invention. 2a is a cross-sectional view taken along line AA in FIG. 2b is a cross-sectional view taken along line BB in FIG. FIG. 3A is a view showing an arrangement example of a plasma torch and a laser head with respect to a material to be welded. FIG. 3b is a view showing an arrangement example of a plasma torch and a laser head with respect to a material to be welded. FIG. 3c is a schematic view seen from the traveling direction of the material to be welded in order to explain the angle between the plasma torch and the laser head. FIG. 4 is a plan view showing a welded portion and its periphery in order to explain the welding method of the present invention. FIG. 5 is a schematic cross-sectional view for explaining the multiple reflection effect of the laser beam that occurs inside the V-shaped groove. FIG. 6 is a schematic cross-sectional view for explaining the penetration depth and the bead width. FIG. 7a is a graph showing the relationship between the welding speed, penetration depth, and bead width at the time of plasma single welding. FIG. 7b is a graph showing the relationship between the welding speed, the penetration depth, and the bead width during plasma single welding. FIG. 8 is a graph showing the relationship between the welding speed, penetration depth, and bead width at the time of laser independent welding. FIG. 9a is a graph showing the relationship between the center-to-center distance of the heat input region by two heat sources, the bead width, and the penetration depth when both plasma welding and laser welding are performed. FIG. 9B is a graph showing the relationship between the center-to-center distance of the heat input region by two heat sources, the bead width, and the penetration depth when both plasma welding and laser welding are performed.

Claims (16)

Continuously supplying materials to be welded having welds facing each other;
Preheating the weld with a plasma torch;
A continuous butt welding method using plasma and laser, including the step of irradiating and welding a laser beam to the welded portion preheated by the plasma torch. The continuous butt welding method using plasma and laser according to claim 1, wherein a butt interval between the welds facing each other is 0.2 mm or less. The plasma and laser according to claim 1, wherein a distance between the center of the heat input region by the plasma torch and the center of the heat input region by the laser beam is 0.5 to 2.5 mm. Had continuous butt welding method. 2. The continuous matching using plasma and laser according to claim 1, wherein an included angle between a plasma discharge direction of the plasma torch and an irradiation direction of the laser beam is within 70 °. Welding method. The plasma discharge direction by the plasma torch and the irradiation direction of the laser beam have an angle within ± 20 ° with respect to the welded portion when viewed from the traveling direction of the workpiece. 2. A continuous butt welding method using the plasma and laser according to 1. The welded material is one or two of stainless steel, nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium alloy, mild steel, and low alloy steel. Continuous butt welding method using plasma and laser. 2. The continuous butt welding using plasma and laser according to claim 1, wherein the material to be welded is supplied such that a cross-sectional shape of the welded portion forms a V-shaped groove and faces each other. Method. 8. The continuous butt welding method using plasma and laser according to claim 7, wherein the included angle of the V-shaped groove is 40 [deg.] Or less. Continuously supplying a strip-shaped metal sheet;
Processing into a tubular shape so that both sides of the metal plate face each other;
Manufacturing a metal tube comprising the steps of preheating welds that are processed into a tubular shape and facing each other using a plasma torch, and irradiating the welds preheated by the plasma torch with a laser beam. Method. The metal pipe manufacturing method according to claim 9, wherein a butt interval between the welds facing each other is 0.2 mm or less. The method for manufacturing a metal tube according to claim 9, wherein a distance between the center of the heat input region by the plasma torch and the center of the heat input region by the laser beam is 0.5 to 2.5 mm. The method for manufacturing a metal tube according to claim 9, wherein an included angle between a plasma discharge direction by the plasma torch and an irradiation direction of the laser beam is within 70 °. 10. When viewed from the traveling direction of the metal plate, the plasma discharge direction by the plasma torch and the laser beam irradiation direction have an angle within ± 20 ° with respect to the welded portion. The manufacturing method of the metal pipe as described in any one of. The metal plate according to claim 9, wherein the metal plate material is made of any one of stainless steel, nickel alloy, copper, copper alloy, aluminum, aluminum alloy, titanium alloy, mild steel, and low alloy steel. Production method. 10. The method of manufacturing a metal tube according to claim 9, wherein, in the step of processing into a tubular shape, both side portions of the metal plate material are processed so that cross-sectional shapes face each other while forming a V-shaped groove. The metal tube manufacturing method according to claim 15, wherein an included angle of the V-shaped groove is 40 ° or less.

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